1. Field of the Invention
The present invention relates to a display device, and more particularly, to a tiled display.
2. Background of the Related Art
As visual information transmitting devices become increasingly important, the scope of an electronic display device industry is being enlarged. The demand for a liquid crystal display (LCD) device, one of the electronic display devices, which is desirably thin and light and consumes small power, is rapidly increasing. Also, with the improved standard of living of consumers, a product having a larger size and better image quality is in more demand.
However, the LCD device has a limit in implementing a large screen by enlarging a size of a liquid crystal panel itself because of its own characteristics. Thus, what is called a projection TV having an optical system with a small liquid crystal panel and implementing a large image by magnifying and projecting an image on the screen has emerged. Recently, a tiled liquid crystal display device in which several liquid crystal devices are tiled side by side to form a large size display device is being put to practical use.
As disclosed in U.S. Pat. Nos. 4,980,755, 5,067,021, 5,068,740 and 5,079,636, the tiled LCD device is fabricated by tiling at least two liquid crystal panels side by side. A key to fabricating such a tiled LCD device is to prevent boundary lines between a plurality of liquid crystal display devices from being displayed on a screen.
FIG. 1 is a schematic construction view which illustrates a related art tiled display device. The tiled display device 10 is formed by fixing a plurality of display panels 30a-30d to a frame 20. The frame includes an outer wall frame 20a forming an outer wall, a partition wall frame 20b interposed between the plurality of display panels 30a-30d, and a bottom plate 20c which the display panels 30a-30d are placed on. Here, each of the display panels 30a-30d is received in a space formed by the partition wall frame 20b and the outer wall frame 20a and is tiled.
However, in a large screen formed through the aforementioned tiling technology, because an image is not formed at an area of the support frame 20, a seam phenomenon (artificial boundary) occurs in that a boundary line is displayed on the screen corresponding to the support frame 20, including the partition wall frame 20b. Thus, an entirely-unified image cannot be displayed.
Accordingly, in order to prevent a seam line from being displayed at a seam area between display devices, namely, at a partition wall frame area, a method of guiding light emitted from the display panels and thus extending a path of the light up to an upper portion of the partition wall frame has been proposed. Here, one of light guides introduced for light diffusion is an optical fiber bundle.
The optical fiber bundle includes an image receiving surface receiving a light source and an image, and a display surface reproducing the received light source and image on a screen of the tiled display device. The light source and the image are magnified by using a difference in distribution density of optical fibers on the image receiving surface and the display surface. Namely, as the display surface has a wider area than that of the image receiving surface to make the optical fiber distribution density on the display surface smaller than that on the image receiving surface, an area of a dead zone between the optical fibers is increased. Accordingly, a light source and an image are magnified and displayed.
However, in the optical fiber bundle that magnifies a light source and an image in the aforementioned manner, because the display surface has a sectional area wider than that of the image receiving surface, optical fibers disposed at a region adjacent to an outer inclined surface are inclined at an angle greater than that at which optical fibers disposed at a central portion are inclined. For this reason, a dead zone between optical fibers on an edge portion becomes wider than that at a central portion.
Accordingly, the brightness of an image transmitted to the edge portion of the optical fiber bundle becomes lower than that of an image transmitted to its central portion, which causes the brightness of an image implemented on a seam area to be different from the average brightness of an entire image. Therefore, a method for achieving uniform brightness distribution over an entire screen of the tiled display device is required.